Kerry was brushing up his Japanese when we went to see him.【误译】当我们去看克里时， 他正在擦(他写错了的)日文字。

【正确】但我们去看克里时， 他正在复习日语。

说明： brush up 是习语 (动词短语)， 意为"复习; 重新学习". 上例也可写成 Kerry was brushing up on his Japanese when we went to see him. 即在 up 后加上 on, 这是美国用法。